Mep-831a

[sassriverrat]

Hey,
Does anyone know what the slave receptacle on the MEP-831A puts out? Wondering if I can bulk charge 24v batteries though.

 

[Cord]

It's rated for 10 amps; that's 1,200 watts at 120 volt.

Never mind, I was thinking the accessory outlet.

 

[kloppk]

The battery charger in the 831 can only output a few amps so it's not going to charge an external battery very fast.
The spec sheet for the charger doesn't clearly specify it's output capability but it eludes to it being capable of something between 3 and 7 amps.
Of course the 831 will use some of that to current to charge it's battery and run the fuel pump, inverter cooling fan and fault circuitry.

 

[Guyfang]

The battery charger in the 831 can only output a few amps so it's not going to charge an external battery very fast.
The spec sheet for the charger doesn't clearly specify it's output capability but it eludes to it being capable of something between 3 and 7 amps.
Of course the 831 will use some of that to current to charge it's battery and run the fuel pump, inverter cooling fan and fault circuitry.

True. But in the army, its used very often to do just that. Charge other batteries. You just need to have enough time. Is it good for the gen set?, well, I don't think so. But for charging some batteries in another set, or a truck, its probably OK. Just not days on end.

 

[sassriverrat]

I figured I could bulk charge off the slave port but guess not. I presume it’s just tied into the battery then....

 

[kloppk]

... I presume it’s just tied into the battery then....

Correct
SR1 below is the Slave Port

 

[sassriverrat]

Ahhh now that is a useful piece to see. Sad that I can't bulk charge batteries with it but good to know. Thanks!!

Side note: Anyone here have any experience with Spartan Inverter/Chargers? Looking to buy a 24v 2200 or 3300 watt unit.

Also experience with diesel truck water heaters?

Thanks!

 

[kloppk]

...Anyone here have any experience with Spartan Inverter/Chargers? Looking to buy a 24v 2200 or 3300 watt unit...Thanks!

I looked at these a couple of weeks ago but ruled them out due to their poor THD specification.
The Manual for the 24V 2200 specs the THD at: "an average THD of 15% (min 5%, max 25%) depending of load connected and the battery voltage"
If your loads aren't fussy about THD then it may be OK for your application.

 

[sassriverrat]

I looked at these a couple of weeks ago but ruled them out due to their poor THD specification.
The Manual for the 24V 2200 specs the THD at: "an average THD of 15% (min 5%, max 25%) depending of load connected and the battery voltage"
If your loads aren't fussy about THD then it may be OK for your application.

Hmmm...So out of curiousity because I am not well-read on THD:
Any idea what the THD on the MEP-831A is? I would imagine fairly low as the 832 would power radio equipment which I would think would be very susceptible.
2. THD is essentially the measure of fluctuation in frequency, right?
3. Would you be worried about a 15% THD for most things?
4. What did you go with for an alternative?

Thanks for the great info and your time!

 

[kloppk]

Hmmm...So out of curiousity because I am not well-read on THD:

THD is Total Harmonic Distortion. An ideal AC voltage is a pure sine wave with absolutely no distortion to the "signal".
Something close to this..


Usually THD on a cheap inverter or cheap generators output usually appears as noise and sometimes distortion of the sine wave.
This example shows both types of distortion

..Any idea what the THD on the MEP-831A is?

< 1%

2. THD is essentially the measure of fluctuation in frequency, right?

As mentioned above it's any distortion from a "pure" sine wave.

What did you go with for an alternative?

For my needs I ended up buying an 1,500 watt 48 V inverter with a <5% THD spec.

 

[sassriverrat]

Thank you for the excellent pictures! That makes better sense. What brand did you end up going with? And essentially, the higher THD begins to act like a "modified Sine Wave", agreed? At least that's how it appears to me, and if I remember, modified sine wave inverters (cheap) are notorious for burning up chargers or batteries in our everyday electronics, right??

 

[kloppk]

A Samlex Inverter
A modified sine inverter output is extreme THD - LOL
Yes - Modified Sine Wave inverters can kill sensitive electronics such as chargers. They also cause a lot of excessive heating in motor windings.
The output of a typical modified sine wave inverter below. Just nasty...

 

[sassriverrat]

Hmmm....makes sense. I remember the chargers being an issue but I hadn't even thought about motor windings....that makes total sense- no smooth transition of current (the sine wave).

What is a "LOT" of THD? Would you say, then, that up to 25% would be way too much for some stuff like a hot water tank, cell phone/laptop (the concerns), mini fridge (household unit?).

Thanks, seriously!

 

[sassriverrat]

@kloppk

Are you enjoying the samlex? Now looking between 2224 and conext 2540.

THanks!